This invention relates to a system for monitoring the weight of a patient, and more particularly to a system for determining either the total weight or a change in the weight of a patient without disturbing the patient in any way.
In the treatment of small children and particularly infants, the quantity of medicine and other substances which are administered are now determined almost exclusively by the weight of the patient. It is therefore imperative to know the precise weight of the patient in order to assure the administration of the proper dosage of a medicine, etc. The determination of changes in the weight of the patient is also imperative not only in order to properly adjust the dosage of the medicine, etc. that is being administered, but also to determine the effect that the particular treatment is having on the patient.
Notwithstanding the necessity of knowing both the total weight and any change in the weight of an infant patient in order to facilitate proper treatment of the patient, there does not presently exist any satisfactory method for weighing critically ill babies. Thus, in accordance with current practices, it is necessary to remove an infant patient from the crib, incubator, etc. and to weigh the patient by means of a conventional baby scale of the type comprising a semicylindrical pan for receiving the patient and a pivoted beam having weights slidably supported thereon for use in determining the weight of the patient. While this procedure is satisfactory in the case of healthy babies, it will be understood that it can be very traumatic in the case of sick children, and can be totally unworkable in those instances in which catheters are in place or the infant is otherwise undergoing treatment.
There also exists a technique for weighing infants within an incubator enclosure. By means of this technique, the baby is positioned in a sling which is supported by a slender cable extending upwardly through the top of the incubator. The cable is connected to a scale supported on the top of the incubator which is utilized to weigh the baby. While this procedure eliminates the need of removing the infant from the incubator in order to determine his weight, it does not eliminate the necessity of disturbing the patient to a substantial extent in order to place him in and subsequently remove him from the weighing sling.
An accurate determination of at least changes in weight is also highly desirable during certain medical treatment procedures relating to adults. An example is that of kidney dialysis where changes in weight are utilized to determine the extent of treatment, and another example is in surgery where a determination of change of weight would be most helpful in determining the extent of blood loss, etc. In the case of kidney dialysis it is presently necessary to place the patient in a bed or chair which is situated on a scale mounted in the floor. While this technique is satisfactory for treatment facilities in which the scales are used relatively continuously, it is prohibitively expensive in those instances in which kidney dialysis treatment is performed infrequently. In the case of surgery, there does not presently exist a satisfactory system for determining changes in weight during the operating procedure.
The present invention relates to a system for monitoring the weight of a patient which overcomes the foregoing and other disadvantages long since associated with the prior art. In accordance with the broader aspects of the invention, there is provided a surface for receiving and supporting a patient with the entire weight of the patient supported by the surface. Structure is provided for producing an output indicative of the total load supported by the patient receiving and supporting surface. By this means the total weight of a patient and/or changes in the weight of a patient may be determined.
In accordance with more specific aspects of the invention, the patient receiving and supporting surface comprises a substantially horizontally disposed patient receiving and supporting surface. This surface is supported on a fluid layer so that the pressure within the fluid layer is indicative of the total load supported by the patient receiving and supporting surface. Transducer apparatus is provided which is responsive to the pressure of the fluid layer to produce an output indicative of the total load supported by the patient receiving and supporting surface, which in turn facilitates a determination of either the total weight of the patient or a change in the weight of a patient.
The patient receiving and supporting surface may comprise the upper surface of a flexible envelope having the fluid layer contained therein. In one embodiment of the invention such a device is positioned within an incubator to facilitate weighing of an infant patient housed therein without disturbing the patient in any way. In another embodiment of the invention a fluid-filled flexible envelope is incorporated in a portable infant weighing system adapted to facilitate both the determination of and the recording of the weight of healthy babies. In this embodiment a rigid patient receiving and supporting member is supported on the flexible envelope so as to eliminate any inaccuracy relating either to the physical size or movements of the patient. In still another embodiment of the invention the fluid-filled flexible envelope structure is utilized in conjunction with an otherwise conventional operating table to facilitate adult treatment procedures such as kidney dialysis, surgery, etc.
In a further embodiment of the invention a rigid patient receiving and supporting member is supported by a plurality of load cells. The output of the load cells is integrated to produce an output indicative of the total load supported by the rigid member, and this output is in turn utilized to generate a visual readout indicative either of the total weight of a patient or of a change in the weight of a patient.
A still further embodiment of the invention is adapted to facilitate breathing of patients having severe fluid retention by supporting such patients in a head-elevated condition. In this embodiment the patient receiving and supporting structure may comprise either rigid members supported on load cells or a plurality of flexible but non-elastic envelopes.